Haemophilus influenzae type B and Hib Vaccine

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1 Haemophilus influenzae type B and Hib Epidemiology and Prevention of - Preventable Diseases Note to presenters: Images of vaccine-preventable diseases are available from the Immunization Action Coalition website at National Immunization Program Centers for Disease Control and Prevention Revised January 2006 Severe bacterial infection, particularly among infants During late 19th century believed to cause influenza Immunology and microbiology clarified in 1930s Haemophilus influenzae Aerobic gram-negative bacteria Polysaccharide capsule Six different serotypes (a-f) of polysaccharide capsule 95% of invasive disease caused by type b Pathogenesis Organism colonizes nasopharynx In some persons organism invades bloodstream and cause infection at distant site Antecedent upper respiratory tract infection may be a contributing factor Clinical Features* Epiglottitis 17% Pneumonia 15% Osteomyelitis 2% Arthritis 8% Cellulitis 6% Bacteremia 2% Meningitis 50% *prevaccination era 1

2 Meningitis Accounted for approximately 50%-65% of cases in the prevaccine era Hearing impairment or neurologic sequelae in 15%-30% Case-fatality rate 2%-5% despite of effective antimicrobial therapy Medical Management Hospitalization required Treatment with an effective 3rd generation cephalosporin, or chloramphenicol plus ampicillin Ampicillin-resistant strains now common throughout the United States Epidemiology Reservoir Human Asymptomatic carriers Incidence*of Invasive Hib Disease, Transmission Temporal pattern Respiratory droplets Peaks in Sept-Dec and March-May Incidence Communicability Generally limited but higher in some circumstances Year *Rate per 100,000 children <5 years of age, 1986 Incidence* by Age Group Incidence Age group (mos) United States, Incidence has fallen 99% since prevaccine era 341 confirmed Hib cases reported during (average of 68 cases per year) Most recent cases in unvaccinated or incompletely vaccinated children *Rate per 100,000 population, prevaccine era 2

3 Risk Factors for Invasive Disease Exposure factors household crowding large household size child care attendance low socioeconomic status low parental education school-aged siblings Host factors race/ethnicity chronic disease Polysaccharide Available Not effective in children <18 months of age Effectiveness in older children variable Polysaccharide s Age-related immune response Not consistently immunogenic in children 2 years old No booster response Antibody with less functional activity Polysaccharide Conjugate s Stimulates T-dependent immunity Enhanced antibody production, especially in young children Repeat doses elicit booster response Conjugate s Conjugate Hib s 3 conjugate vaccines licensed for use in infants as young as 6 weeks of age All utilize different carrier proteins 2 combination vaccines available that contain Hib vaccine HbOC PRP-T PRP-OMP Hibtiter ActHIB, TriHIBit PedvaxHIB, COMVAX 3

4 Routine Schedule 2 mo 4 mo 6 mo mo HbOC x x x x PRP-T x x x x PRP-OMP x x x Recommended interval 8 weeks for primary series doses Minimum interval 4 weeks for primary series doses Vaccination at <6 weeks of age may induce immunologic tolerance to Hib antigen Minimum age 6 weeks Interchangeability All conjugate Hib vaccines interchangeable for primary series and booster dose 3 dose primary series if more than one brand of vaccine used Delayed Vaccination Schedule Children starting late may not need entire 3 or 4 dose series Number of doses child requires depends on current age All children months of age need at least Detailed Schedule for Unimmunized Children Age at 1st Dose (months) Primary series Booster HbOC/PRP-T doses, 2 m apart 2 doses, 2 m apart months months 2 months later Lapsed Immunization Children who have fallen behind schedule with Hib vaccine may not need all the remaining doses of a 3 or 4 dose series PRP-OMP doses, 2 m apart 2 doses, 2 m apart months months 2 months later -- The number of doses needed to complete the series should be determined using the catch-up schedule*, published annually with the childhood schedule *available on the NIP website at 4

5 Vaccination Following Invasive Disease Children <24 months may not develop protective antibody after invasive disease Vaccinate during convalescence Complete series for age Use in Older Children and Adults Generally not recommended for persons >59 months of age Consider for high-risk persons: asplenia, immunodeficiency, HIV infection, HSCT One pediatric dose of any conjugate vaccine Combination s Containing Hib DTaP Hib TriHIBit Hepatitis B Hib COMVAX TriHIBit ActHIB reconstituted with Tripedia Not approved for the primary series at 2, 4, or 6 months of age Approved for the fourth dose of the DTaP and Hib series only Primary series Hib doses given as TriHIBit should be disregarded TriHIBit May be used as the booster dose of the Hib series at >12 months of age following any Hib vaccine series* Should not be used if child has receive no prior Hib doses *booster dose should follow prior dose by >2 months COMVAX Hepatitis B-Hib combination Use when either or both antigens indicated >6 weeks of age Not licensed for use if mother HBsAg+ Spacing and timing rules same as for individual antigens 5

6 Adverse Reactions Swelling, redness, or pain in 5%-30% of recipients Systemic reactions infrequent Serious adverse reactions rare Contraindications and Precautions Severe allergic reaction to vaccine component or following a prior dose Moderate or severe acute illness Age <6 weeks National Immunization Program Contact Information Telephone Website 800.CDC.INFO nipinfo@cdc.gov 6